This invention relates to a method and apparatus for the interrogation of sensors, with particular--but by no means exclusive--reference to semiconducting organic polymer based gas sensors.
There is a great deal of current interest in the use of semiconducting organic polymers in gas sensing applications, since such polymers display rapid gas adsorption/desorption kinetics, relatively high sensitivities and responses which broadly mimic the response of the human olfactory system (see, for example, Persaud K C, Bartlett J G and Pelosi P, in `Robots and Biological Systems: Towards a new bionics?`, Eds. Dario P, Sandini G and Aebisher P, NATO ASI Series F: Computer and Systems Sciences 102 (1993) 579). A typical sensor comprises a pair of electrodes bridged by at least one layer of semiconducting organic polymer; transduction is usually accomplished by measuring changes in the dc resistance of the sensors, these changes being induced by adsorption of gaseous species onto the polymer.